首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   10901篇
  免费   985篇
  国内免费   1019篇
化学   8552篇
晶体学   27篇
力学   81篇
综合类   93篇
数学   2092篇
物理学   2060篇
  2024年   9篇
  2023年   113篇
  2022年   175篇
  2021年   304篇
  2020年   359篇
  2019年   317篇
  2018年   251篇
  2017年   280篇
  2016年   370篇
  2015年   374篇
  2014年   462篇
  2013年   737篇
  2012年   810篇
  2011年   805篇
  2010年   707篇
  2009年   947篇
  2008年   938篇
  2007年   871篇
  2006年   890篇
  2005年   663篇
  2004年   430篇
  2003年   363篇
  2002年   378篇
  2001年   274篇
  2000年   211篇
  1999年   177篇
  1998年   138篇
  1997年   106篇
  1996年   105篇
  1995年   85篇
  1994年   56篇
  1993年   20篇
  1992年   27篇
  1991年   23篇
  1990年   13篇
  1989年   12篇
  1988年   8篇
  1987年   7篇
  1986年   7篇
  1985年   9篇
  1984年   8篇
  1983年   8篇
  1981年   7篇
  1980年   9篇
  1979年   9篇
  1978年   7篇
  1977年   3篇
  1975年   3篇
  1973年   8篇
  1969年   3篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
921.
We discuss Hardy?s paradox and weak measurements by using multitasking diagrams, which are introduced to illustrate the progress of quantum probabilities through the double interferometer system. We explain how Hardy?s paradox is avoided and elaborate on the outcome of weak measurements in this context.  相似文献   
922.
923.
Shudong Li  Lixiang Li  Yixian Yang 《Physica A》2011,390(6):1182-1191
In this paper, we present a novel local-world model of wireless sensor networks (WSN) with two kinds of nodes: sensor nodes and sink nodes, which is different from other models with identical nodes and links. The model balances energy consumption by limiting the connectivity of sink nodes to prolong the life of the network. How the proportion of sink nodes, different energy distribution and the local-world scale would affect the topological structure and network performance are investigated. We find that, using mean-field theory, the degree distribution is obtained as an integral with respect to the proportion of sink nodes and energy distribution. We also show that, the model exhibits a mixed connectivity correlation which is greatly distinct from general networks. Moreover, from the perspective of the efficiency and the average hops for data processing, we find some suitable range of the proportion p of sink nodes would make the network model have optimal performance for data processing.  相似文献   
924.
In this paper, we propose a well targeted algorithm (GAS algorithm) for detecting communities in high clustered networks by presenting group action technology on community division. During the processing of this algorithm, the underlying community structure of a clustered network emerges simultaneously as the corresponding partition of orbits by the permutation groups acting on the node set are achieved. As the derivation of the orbit partition, an algebraic structure r-cycle can be considered as the origin of the community. To be a priori estimation for the community structure of the algorithm, the community separability is introduced to indicate whether a network has distinct community structure. By executing the algorithm on several typical networks and the LFR benchmark, it shows that this GAS algorithm can detect communities accurately and effectively in high clustered networks. Furthermore, we compare the GAS algorithm and the clique percolation algorithm on the LFR benchmark. It is shown that the GAS algorithm is more accurate at detecting non-overlapping communities in clustered networks. It is suggested that algebraic techniques can uncover fresh light on detecting communities in complex networks.  相似文献   
925.
We generalize the usual two-strategy prisoner?s dilemma game to a multi-strategy game, in which the strategy variable s is allowed to take q different fractional values lying between 0 and 1. The fractional-valued strategies signify that individuals are not absolutely cooperative or defective, instead they can adopt intermediate strategies. Simulation results on 1D and 2D lattices show that, compared with the binary strategy game, the multi-strategy game can sustain cooperation in more stringent defective environments. We give a comprehensive analysis of the distributions of the survived strategies and we compare pairwise the relative strength and weakness of different strategies. It turns out that some intermediate strategies survive the pure defection because they can reduce being exploited and at the same time benefit from the spatial reciprocity effect. Our work may shed some light on the intermediate behaviors in human society.  相似文献   
926.
Tatsuaki Wada 《Physics letters. A》2011,375(20):2037-2040
Gauss? principle in statistical mechanics is generalized for a q-exponential distribution in nonextensive statistical mechanics. It determines the associated stochastic and statistical nonextensive entropies which satisfy Greene-Callen principle concerning on the equivalence between microcanonical and canonical ensembles.  相似文献   
927.
红外光谱技术由于其灵敏度高和对样品的非破坏性等优点已成为研究生物大分子损伤的重要工具。蛋白质、脂质和核酸等受到损伤时,其红外光谱特征吸收峰的峰位、峰型和峰强会发生变化,这为检测生物大分子损伤并进一步揭示相关疾病的发生、发展及早期预防提供了依据。还综述了近年来使用红外光谱法检测生物大分子损伤的研究进展,介绍了利用傅里叶变换红外光谱、衰减全反射傅里叶变换红外光谱和傅里叶红外显微等技术在蛋白质二级结构、膜脂流动性和离子通透性以及药物对DNA的作用机制等领域的应用,以及相关的定性和定量分析方法进行了评述,提出了目前红外光谱分析技术中存在的问题,并对今后红外光谱在生物医学领域中的应用前景作了展望,指出疾病早期诊断、红外光谱联用以及定量分析技术等将成为红外光谱领域未来的研究热点。  相似文献   
928.
The generalized trigonometric functions occur as an eigenfunction of the Dirichlet problem for the one-dimensional pp-Laplacian. The generalized hyperbolic functions are defined similarly. Some classical inequalities for trigonometric and hyperbolic functions, such as Mitrinovi?–Adamovi?’s inequality, Lazarevi?’s inequality, Huygens-type inequalities, Wilker-type inequalities, and Cusa–Huygens-type inequalities, are generalized to the case of generalized functions.  相似文献   
929.
930.
The paper deals with the study of complete embedded flat surfaces in H3H3 with a finite number of isolated singularities. We give a detailed information about its topology, conformal type and metric properties. We show how to solve the generalized Weyl?s problem of realizing isometrically any complete flat metric with Euclidean singularities in H3H3 which gives the existence of complete embedded flat surfaces with a finite arbitrary number of isolated singularities.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号